Pi Approximation Day
July 22 · Level 4 · #1491 of 2238
Pi Approximation Day celebrates the fraction 22/7, which comes surprisingly close to pi. The date is written 22/7 in the day-month style, so it is a perfect excuse for a little maths fun.
How it is celebrated: fans of numbers swap puzzles and pi jokes, draw circles with a compass, and eat anything round, from pies to pizza.
The fraction 22/7 is about 3.1429, which is off from the real pi by only around 0.04 percent. The ancient Greek mathematician Archimedes used it as an upper bound for pi.